Reclamation of Wastelands contaminated with Chlor Alkali Sludge

Industrialization has served mankind with numerous technologies that make life easier. But the environmental damage occurring today as a result of industrialization is not to be ignored. The industrial wastes have accumulated in the nearby areas as hardened layers of chemical sludge rendering the land unfit for cultivation. The Energy and Resources Institute (TERI) has found ways to reclaim these wastelands that are heavily laden with chlor alkali sludge, using plants and microorganisms. The green belt developed in the once toxic chemical basin at Tata Chemicals Ltd. (Mithapur), Gujarat is a success story of this reclamation technology.

The issue

The chemical wastes formed out of alkali and chloride rich sediments from industrial discharge was posing a health hazard for the residents of the coastal areas nearby. The highly saline substrate made germination of seeds difficult and leachates from waste area contaminated the low water table. The site had extremely high pH (11.7) and electrical conductivity (74.4 mS/cm2) as compared to the near neutral pH (7.0) and electrical conductivity (near 1 mS/cm2) of normal soil. These values affected the availability of several important nutrients to plants.

The realistic approach

TERI's researchers had isolated and mass multiplied microbes inhabiting the sites that could withstand the onslaught of chemical sludge and applied them to the site. Partially tolerant plant species were planted on a specially designed landscape inoculating it with mycorrhiza to overcome the stressful substrate. Mycorrhizal biofertilizers provide tolerance and strength to the plants to withstand the adverse conditions by enhancing uptake of nitrogen and phosphorous.

Watering was done in stages: initially with sweet water, followed by a combination of sweet water and sea water, and then only with sea water. This endeavour converted the chemical laden site to a lush green plantation of Jatropha curcas (the bio-diesel plant), neem, Paras pepal, aloe vera, acacia, salicornia, and casuarinas.

Future scope

Having met with success in reducing the fugitive dust emissions and ground water leaching, TERI has offered an effective solution for the companies under pressure to adapt to eco-friendly practices. The plants selected to grow on the sludge could be of economic value like Jatropha curcas which yield bio-fuel, Salicornia used in salads, Aloe Vera, valued in cosmetics industry and Casuarina, used in paper industry. Thus, these wastelands could be converted into lands with a huge commercial proposition.

Light of Hope

For sustainable reclamation of the industrial dump yards, usage of native microbes and partially salt tolerant plant species inoculated with mycorrhiza is found to be highly successful.